Effect of molecular weight of dissolved organic matter on toxicity and bioavailability of copper to lettuce  

作　　者：Xudong Wang,Xianni Chen,Shuai Liu,Xizu Ge College of Resource and Environment,Northwest Agriculture and Forestry University,Shaanxi 712100,China 

出　　处：《Journal of Environmental Sciences》2010年第12期1960-1965,共6页环境科学学报（英文版）

基　　金：supported by the Ministry of Science and Technology of China(No. 2007BAD89B16);the National Natural Science Foundation of China(No. 39800093);the Youth Planning Program of Northwest A & FUniversity

摘　　要：To clarify the effects of molecular weight of dissolved organic matter （DOM） on the toxicity and bioavailability of copper （Cu） to plants, DOM extracted from chicken manure was ultra-filtered into four fractions according to their molecular weights by means of sequential-stage ultrafiltration technique. Lettuce seeds were germinated by being exposed to the solutions containing Cu^2＋ with or without different fractions of DOM. The concentration of copper in roots, leaves, sprouts and the length of roots were investigated. The results showed that not all fractions of DOM could improve copper availability or toxicity. The fraction of DOM with larger molecular weight more than 1 kDa had higher complexation stability with Cu^2＋ and caused lower concentration of free Cu^2＋ ion in the solution of copper plus the fraction, resulting in lower availability and toxicity of copper to lettuce, but the fraction with molecular weight less than 1 kDa had the opposite function. Therefore, the molecular weight of 1 kDa may be the division point to determine DOM to increase or decrease copper availability and toxicity.To clarify the effects of molecular weight of dissolved organic matter （DOM） on the toxicity and bioavailability of copper （Cu） to plants, DOM extracted from chicken manure was ultra-filtered into four fractions according to their molecular weights by means of sequential-stage ultrafiltration technique. Lettuce seeds were germinated by being exposed to the solutions containing Cu^2＋ with or without different fractions of DOM. The concentration of copper in roots, leaves, sprouts and the length of roots were investigated. The results showed that not all fractions of DOM could improve copper availability or toxicity. The fraction of DOM with larger molecular weight more than 1 kDa had higher complexation stability with Cu^2＋ and caused lower concentration of free Cu^2＋ ion in the solution of copper plus the fraction, resulting in lower availability and toxicity of copper to lettuce, but the fraction with molecular weight less than 1 kDa had the opposite function. Therefore, the molecular weight of 1 kDa may be the division point to determine DOM to increase or decrease copper availability and toxicity.

关 键 词：fraction of dissolved organic matter complexation stability coooer availability 

分 类 号：X173[环境科学与工程—环境科学]